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Home >> Chevrolet >> 2000 >> Tracker 4D Utility, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0121: Throttle Position Sensor Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Check if DTC P0122 or P0123 is set. If DTC P0122 or P0123 is also set, diagnose affected DTC(s) first. If DTC P0122 or P0123 is not set, go to next step.
  3. Warm engine to normal operating temperature. Turn ignition on, with engine off. Install scan tool. Observe TP sensor parameter on scan tool. If scan tool displays 0.2-1.0 volts with throttle at idle position and 3.4-4.7 volts with throttle at WOT, go to next step. If scan tool display is not 0.2-1.0 volts with throttle at idle position and 3.4-4.7 volts with throttle at WOT, go to step  5.
  4. Turn ignition on, with engine off. Using scan tool, clear DTCs. Operate vehicle within FREEZE FRAME conditions. Retrieve DTCs. If this DTC resets, go to next step. If this DTC does not reset, see DIAGNOSTIC AIDS .
  5. Turn ignition off. Disconnect TP sensor harness connector. Using DVOM, check resistance between TP sensor harness connector terminals No. 1 (TP sensor ground circuit) and No. 3 (reference voltage circuit). If resistance is 4000-6000 ohms, go to next step. If resistance is not 4000-6000 ohms, go to step  8.
  6. Ensure throttle plate is closed (at idle). Check resistance between TP sensor harness connector terminals No. 1 (TP sensor ground circuit) and No. 2 (TP sensor input circuit). If resistance is 500-1000 ohms, go to next step. If resistance is not 500-1000 ohms, go to step  8.
  7. Connect DVOM between TP sensor terminals No. 1 (TP sensor ground circuit) and No. 2 (TP sensor input circuit). Slowly move throttle from closed to open while observing DVOM. If resistance changes smoothly from low to high while remaining within 500-6000 ohms, go to step  9. If resistance does not change smoothly from low to high while remaining within 500-6000 ohms, go to next step.
  8. Replace TP sensor. After replacing sensor, go to step  11.
  9. Check for high resistance, short to ground or short to voltage in TP sensor input circuit. Check for high resistance in TP sensor ground circuit. Check for poor connection at PCM. Repair as necessary. After repairs, go to step  11. If circuits and connection are okay, go to next step.
  10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  11. After repairs, clear DTCs. Operate vehicle within FREEZE FRAME conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).
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